With the development of network information and associated technologies, a navigation device or the navigation software in a mobile device almost become a driving must. However, if the driver distracts to look down or turn to watch the navigation information that is shown on the navigation device or the navigation software in the driving process, the driving safety is adversely affected and the life safety is possibly endangered. For reducing the traffic safety hazards of turning to watch the driving dashboard or the navigation device while watching the traffic condition, a head-up display is introduced into the market. The head-up display is shown on a windshield of a vehicle. Since a portion of the driving information of the driving dashboard is shown on the windshield according to a projecting technology, the driver can simultaneously watch the traffic condition and a portion of the driving information of the driving dashboard through the windshield.
Since the head-up displays are expensive, only few luxury vehicles have the built-in head-up displays. The other vehicles are optionally equipped with the head-up display at their own expense. In other words, it is difficult to popularize the use of head-up display. Moreover, the existing head-up display only provide the navigation information that is shown on the navigation device or the navigation software. As known, the driving information provided by the existing head-up display is usually insufficient. Consequently, the head-up display is not favored by many drivers.
Taiwanese Patent Publication No. 200848703 discloses a navigation assistance using a camera. A navigation device and a camera cooperate with each other to superimpose the navigation information on a captured image of the camera. Through the captured image, the driver can simultaneously watch the traffic condition and the navigation information. However, the display device of the camera cannot show sufficient traffic information, navigation information and driving safety prompt information on the same captured image. For example, the driving speed, the gearshift status, the gasoline capacity and other driving status information of the vehicle cannot be shown on the captured image. Under this circumstance, the driver has to look down the dashboard to realize the driving information.
Taiwanese Patent No. 1521484 discloses a device for simultaneously showing the navigation information and the driving safety prompt information. Under control of a host, the information on a camera unit, the information on a navigation unit and the information on a driving safety prompt unit are collaboratively shown on a display unit. Consequently, the traffic condition image, the navigation information, the front car safety distance and other required information are simultaneously shown on the display unit. Through the display unit, the driver can realize the real-time traffic condition image, the navigation information and the driving safety information. Since the driver does not need to turn to different positions to watch the driving information, the driving disaster caused by distraction is reduced and the driving safety is enhanced.
With increasing development of wireless transmission technologies, the above purpose can be achieved by using the wireless transmission technologies. Take the patent of Taiwanese Patent No. 1521484 as an example. The display unit, the camera unit, the navigation unit and the audio prompt unit are wirelessly connected with the host according to wireless transmission technologies. Consequently, the display unit, the camera unit, the navigation unit and the audio prompt unit are placed on the suitable positions without being restricted by the connecting wires. That is, these components can be easily installed. However, during the wireless transmission process, the image shown on the display unit is suffered from a display lag problem. For example, if the navigation unit wirelessly transmits the navigation information to the host while the camera unit wirelessly transmits the traffic condition image to the host, the host firstly performs the wireless transmission of the traffic condition image and then performs the wireless transmission of the navigation information. After the navigation information is transmitted to the host, the host will show the traffic condition image and the navigation information on the display unit. That is, the image is shown on the display unit after all data have been transmitted to the host. Consequently, the display lag problem occurs.
Therefore, there is a need of providing a vehicular projection system for solving the display lag problem.